Curriculum designers often assume that teachers implement curricula as written, yet research shows that all teachers adapt curricula. Adaptation is especially important in the context of sustained curriculum implementation, as some level of adaptation may be necessary for teachers to feel ownership over a program. However, whereas some adaptations are productive, others undermine program effectiveness. This study identifies, describes, and evaluates adaptations to a literacy intervention curriculum for struggling adolescent readers. Data were collected through observation and interviews of 2 teachers in a school that had sustained implementation of a literacy curriculum after the conclusion of the intervention study. Six focal adaptations were identified--3 from each teacher--and analyzed for productivity. Of the 6 adaptations, only 2 met criteria for productivity. This suggests that making productive adaptations is difficult and that teachers should be supported in productively adapting curricula through educative curriculum materials and effective professional development.